1. Field of the Invention
The invention relates to a touch panel input coordinate transform device and a method of transforming a touch panel input coordinate and, in particular, to the device and the method which are suitable for rotating displayed images.
2. Description of the Related Art
In the prior art, a touch panel input system has a touch panel module and a display unit. The touch panel module includes an origin register unit which registers an origin and a transform unit which transforms physical coordinates touched into logical coordinates by using origin information representative of the origin.
When the touch operation is carried out on the physical coordinates drawn on the display unit, the transform unit transforms the physical coordinates into the logical coordinates using the information on the origin and transfers the transformed logical coordinates to an input control unit as input coordinates.
However, a conventional touch panel system must register the origin again each time when images displayed on the display unit are rotated. This is because data touched and input on physical coordinates after the rotation of the images are merely transformed into logical coordinates which are defined before the rotation and which are different from those after the rotation.
Therefore, it is an object of the invention to provide a touch panel system which requires no origin registration even if images displayed are rotated.
According to a first aspect of the invention, there is provided a touch panel input coordinate transform device. The device comprises a first storage unit which stores first rotation information on images displayed on a display including a touch panel when an origin of the touch panel is registered, a second storage unit which stores second rotation information on images currently displayed on the display, a comparison unit which compares the first rotation information with the second rotation information when a touch operation is performed onto the touch panel, and determines a difference between them, and a transform unit which transforms coordinates where the touch operation is performed, on the basis of the difference when the contents of the first rotation information is different from the contents of the second rotation information.
According to a second aspect of the invention, there is provided a method of transforming a touch panel input coordinate. The method comprises the steps of storing, in a first storage unit, first rotation information on images displayed on a display including a touch panel when an origin of the touch panel is registered, comparing the first rotation information with second rotation information stored in a second storage unit when a touch operation is performed onto the touch panel, and determining a difference between them, and transforming coordinates where the touch operation is performed, on the basis of the difference when the contents of the first rotation information is different from the contents of the second rotation information.
According to a third aspect of the invention, there is provided a recording medium readable by a computer, tangibly embodying a program of instructions executable by the computer to perform a method of transforming a touch panel input coordinate. And the method comprises the steps of storing, in a first storage unit, first rotation information on images displayed on a display including a touch panel when an origin of the touch panel is registered, comparing the first rotation information with second rotation information stored in a second storage unit when a touch operation is performed onto the touch panel, and determining a difference between them, and transforming coordinates where the touch operation is performed, on the basis of the difference when the contents of the first rotation information is different from the contents of the second rotation information.